Schwenk, Tilmann and Spiess, Volkhard (2009): Architecture and stratigraphy of the Bengal Fan as response to tectonic and climate revealed from high-resolution seismic data

Leg/Site/Hole:
DSDP 22
DSDP 22 218
Identifier:
2010-037425
georefid

Creator:
Schwenk, Tilmann
Universitaet Bremen, Fachbereich Geowissenschaften, Bremen, Federal Republic of Germany
author

Spiess, Volkhard
StatoilHydro, Norway
author

Identification:
Architecture and stratigraphy of the Bengal Fan as response to tectonic and climate revealed from high-resolution seismic data
2009
In: Kneller, Ben (editor), Martinsen, Ole J. (editor), McCaffrey, Bill (editor), External controls on deep-water depositional systems
Society for Sedimentary Geology (SEPM), Tulsa, OK, United States
92
107-131
High resolution seismic data collected on four profiles located on the Bengal Fan at 8 degrees N, 11 degrees N, 14 degrees N, and 17 degrees N were analyzed. Numerous channel-levee systems were identified as main architectural elements, all characterized by erosional incision into underlying sediments. On the upper middle fan (17 degrees N), the channel-levee systems are grouped into four complexes. They are separated by regional unconformities, which were partly caused by generation of nonchannelized turbidity currents or switching of the feeding canyon. Succession of the systems and dating of two surface channels (Weber et al., 1997; Weber et al., 2003) indicate activity of the Bengal Fan even during sea-level rises and highstands. In all three profiles from the lower fan, two regional unconformities were found. At 8 degrees N, the unconformities could be dated at DSDP Site 218 to have Pliocene and Pleistocene ages, and were interpreted to be the equivalents of unconformities found in the central Indian Ocean, which are caused by deformation events of the oceanic crust (Krishna et al., 2001a). Faults terminating within Pleistocene sediments suggest tectonic activity at least within the Pleistocene at 8 degrees N. The unconformities identified at 11 degrees N and 14 degrees N may also result from tectonic events. Besides these unconformities, variations of sedimentation rates in time and space determined at 8 degrees N and the onset of channel-levee systems simultaneously with lithological changes at ODP Leg 116 sites suggest that tectonic events at the Bengal Fan as well as changes of sediment supply and transport occurred partly concurrently. The sediment supply in turn depends on the erosional regime in the Himalayas, which is controlled by tectonic or climate or an interaction of both. Therefore we propose that a tectonic link may exist between source and sink areas of Bengal Fan turbidites, i.e., between uplift of the Himalayas and deformation events of the Indian Ocean lithosphere.
English
Serial
Coverage:Geographic coordinates:
North:8.0026
West:86.1658East: 86.1659
South:8.0025

Quaternary geology; Applied geophysics; Asia; Bangladesh; Bay of Bengal; Bengal Fan; Cenozoic; channels; clastic sediments; climate change; continental margin sedimentation; currents; Deep Sea Drilling Project; depositional environment; DSDP Site 218; fluvial features; geometry; geophysical methods; geophysical surveys; high-resolution methods; highstands; Himalayas; Indian Ocean; Indian Peninsula; Leg 22; levees; lithostratigraphy; marine sedimentation; neotectonics; paleoclimatology; paleoenvironment; Pleistocene; Quaternary; rivers; sediment supply; sediment transport; sedimentation; sedimentation rates; sediments; seismic methods; seismic stratigraphy; submarine fans; surveys; tectonics; turbidite; turbidity currents; unconformities;

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